Water-soluble polymers are widely used in oil and gas recovery processes, such as enhanced oil recovery and hydraulic fracturing operations, but also other stimulation, cementing, drilling operations or completion operations. Water-soluble polymers are generally in solution form, in inverse emulsion form, in powder form, or in dispersion form. Each of them has known advantages and drawbacks.
In the oil and gas industry, there is generally a need for highly concentrated version of polymer composition, easily useable, and hence preferably in liquid form. The document WO2017/187150 proposes a formulation prepared by mixing a granulated water-soluble friction reducing polymer with an inverse polymer emulsion. This offers a liquid composition that does not require specialized equipment and which is found to be technically advantageous and cost-effective. More precisely, the composition affords friction reducing performances that matches or surpasses previous friction reducers. The level of friction reduction is higher and reached faster.
In oil and gas operations, fluids that are injected into a subterranean formation may comprise particles or colloids. In that case, the particles or colloids have to be suspended in the fluid in order to avoid any sedimentation and inhomogeneity of the dispersed particles. Viscosifying polymers are generally used for that purpose in injection fluid compositions. However, the injection fluid composition is generally exposed to high shear conditions and the viscosifying polymers which are generally shear thinning do not afford satisfactory results.
There is a need to improve the viscosity and/or the suspensive effect(s) of water-soluble polymers used in oil and gas recovery processes, especially when high shear conditions are encountered.
In fracturing operation, especially when High Viscosity Friction Reducers (HVFR) are used, the dosage of said HVFR is important and there is a need to improve their efficiency at same dosage, or to have the same efficiency at lower dosage.
The applicant has developed a new composition made with a combination of specific water-soluble polymers and that offers solutions to the problem above described.